Crystal Structure and Magnetic Behavior of the Decamethylferrocenium and Decamethylchromocenium Salts of Bis(Ethylenedithiolato)Nickel, [M(Cp*)(2)][Ni(Edt)(2)] - Magnetic Anisotropy and Metamagnetic Behavior of [Fe(Cp*)(2)[Ni(Edt)(2)]